Electrochromic contrast plate

ABSTRACT

The invention relates to an electrochromic contrast plate which is either arranged as a discrete unit in front of the screen or is connected to the outer surface of the screen through a common sheet, consisting of a pair of transparent glass or plastic sheets which are provided, on one side each, with an electroconductive, transparent coating, and which are joined together on the sides of their conductive coating via a sealing ring, and in which the volume formed by the two sheets and the sealing ring is filled with an electrochromic medium, characterized in that the electrochromic medium is a liquid, a gel or a polymer. The invention furthermore relates to an electrochromic contrast plate with integrated touch screen which has a larger base area than the area of the screen, and, at at least one of the faces of the outer sheet (outer plate) of the electrochromic contrast plate, a radiation source is arranged whose light enters the outer plate and illuminates it, and, at the inner sheet (carrier plate), in the region which projects beyond the screen area, a photodetector is mounted in whose photosensitive solid-angle region part or all of the carrier plate is located, if it projects beyond the screen area. The invention furthermore relates to electrochromic side-chain oligomers or polymers which can be used as electrochromic media.

[0001] The present invention relates to an electrochromic (EC) contrastplate for display screens whose transmission in the optically visibleregion can be controlled by applying a voltage. The inventionfurthermore relates to an EC contrast plate having an integrated touchscreen. The invention also relates to electrochromic side-chainoligomers and polymers which can be used as electrochromic media.

[0002] In display screens which are operated, in particular, indaylight, the image contrast is frequently lost due to reflection ofambient light on the screen. In the extreme case, the image is virtuallyimpossible to see. This applies in particular to display screens basedon a cathode ray tube (CRT) or on a liquid-crystal display (LCD).

[0003] U.S. Pat. No. 5,847,858 (WO 97/22906) proposes arranging anadditional, colour-neutral filter in front of the screen. Thiscolour-neutral filter is an electrochromic device which functions on thebasis of two different types of metal oxides. The first electrode istreated with a mixture of one or more metal oxides from group 1,consisting of WO₃, MoO₃, Nb₂O₅, MnO₂ and ZrO₂, and group 2, consistingof V₂O₅, TiO₂ and ZnO. The counterelectrode does not contribute towardsmodifying the transmission of the EC device. If this colour-neutralfilter is arranged in front of a display screen, such as, for example, acathode ray tube (CRT), it reduces the intensity of the reflectedambient light and also of the internal light source, such as, forexample, the phosphors of the CRT. The incident ambient light passesthrough the colour-neutral filter and is reflected at the screensurface. The reflected light again passes through the absorbentcolour-neutral filter before exiting. For a transmission T of thecolour-neutral filter, this gives an attenuation by the factor T². Lightoriginating from an internal light source, such as the light from thephosphors, need only pass through the colour-neutral filter once and isthus only attentuated by a factor T. The contrast is thus increased by afactor T¹. This colour-neutral filter is produced by a very complex,expensive sputtering process. In addition, electrochromic colouredfilters of this type are not particularly resistant and do not allow alarge number of switching cycles. Coloured filters based on tungstenoxide/palladium hydride exhibit light scattering and consequently adistortion of the picture and a decrease in contrast.

[0004] Display screens are increasingly being used in aggressiveenvironments, such as, for example, in production operations for processcontrol. The input devices used for computers and electronic measurementand control equipment, in particular in production operations andsimilar environments, in which conventional computer input devices, suchas a mouse or keyboard, wear very quickly owing to the considerable dustand dirt loading, are predominantly touch screens. The image displayedon the touch screens usually consists of some explanatory texts and aseries of fields, the touching of which corresponds to a certain data orcommand input.

[0005] Known touch screens are constructed, for example, fromliquid-crystal displays or cathode ray tubes and an additionaltouch-sensitive device.

[0006] The disadvantage of the known touch screens is firstly that theyrapidly become dirty (systems with light barriers) or age rapidly(system with touch-sensitive membranes).

[0007] The object according to the invention consists in providing adevice for improving the contrast of display screens, while retainingcolour neutrality, which is less complex to produce than thecolour-neutral filters known from the prior art. The device according tothe invention should have a large electrochromic range, beageing-resistant and allow a very large number of switching cycles. Afurther object of the invention is simultaneously to provide a robust,easy-to-clean touch screen with the device for improving the contrast.

[0008] The object according to the invention is achieved by an ECcontrast plate. The EC contrast plate consists of an electrochromicdevice known per se, comprising a pair of glass or plastic sheets whichare provided on one side each with an electroconductive coating, forexample indium-tin oxide (ITO). Both sheets are transparent. Thesesheets are used to construct a cell by connecting them, preferablyadhesively bonding them, to an annular or rectangular sealing ring withtheir electroconductively coated sides facing one another. The scalingring establishes a uniform distance between the sheets, of, for example,from 0.01 to 0.5 mm. This cell is filled with an electrochromic medium.The two sheets can be provided with separate contacts via theelectroconductive layers.

[0009] This EC contrast plate is in accordance with the invention eitherarranged as a discrete unit in front of the display screen or connectedto the outer surface of the screen as one substrate through a commonsheet.

[0010] The EC contrast plate according to the invention contains an ECmedium which is a solution or a gel or a polymer. A medium of this typecan easily be introduced into an electrochromic cell.

[0011] The EC medium comprises a mixture of electrochromic compoundswhich, on application of a voltage, produces a very uniform, neutralgrey coloration or causes any desired other coloration, such as, forexample, a red coloration of the image. The transmission of theelectrochromic layer in the visible region can be varied by varying thestrength of an applied voltage.

[0012] A preferred embodiment of the invention is determined by thecolour coordinates (x, y) of the dyes in the EC medium, which, inaccordance with the C.I.E. standard (regarding the C.I.E. standard, see,for example, Colour Physics in Industry, Roderick McDonald, ed., Societyof Dyers and Colourists, 1987), are in the colour triangle between 0.3and 0.37 or preferably between 0.31 and 0.35.

[0013] In a further, likewise preferred embodiment of the invention, thecolour coordinates of the EC medium in the switched state are inbasically any desired region of colour space, this region beingdetermined by the particular requirements of the application, forexample the exclusion of certain wavelength ranges on use inphotographic development laboratories.

[0014] If no voltage is applied between the two electroconductivelayers, the EC contrast plate is transparent and preferably has atransmission of greater than 70%. The minimum transmission in the caseof colouring is less than 25%. The transmission remains constant overthe entire area, even in the case of curved surfaces, and varies by lessthan 5% in time and space.

[0015] The switching times in which colouring or decolouring occursafter application of a voltage or after switching-off of the voltagerespectively are less than 5 minutes, preferably less than one minute.

[0016] As electrochromic medium, DE 196 05 451 and DE 196 05 448disclose electrochromic systems, which usually contain pairs of redoxsubstances dissolved in an inert solvent. In addition, conductive salts,light stabilizers (UV stabilizers) and substances which modify theviscosity may be present. The pair of redox substances used comprisesone reducible substance and one oxidizable substance. In the groundstate, the two substances are colourless or only weakly coloured. Underthe influence of an electric voltage, the first substance is reduced andthe other oxidized, at least one becoming coloured. When the voltage isswitched off, the ground state is restored in both substances, withdecoloration or colour lightening occurring.

[0017] U.S. Pat. No. 4,902,108 discloses that suitable pairs of redoxsubstances are those whose reducible substance has at least twochemically reversible reduction waves in the cyclic voltammogram andwhose oxidizable substance correspondingly has at least two chemicallyreversible oxidation waves.

[0018] The electrochromic systems from DE 196 05 448 and DE 196 05 451comprise at least one oxidizable substance RED₁, and at least onereducible substance OX₂, which, respectively through electron donationat an anode and electron acceptance at the cathode, are converted from aweakly coloured or colourless form into a coloured form OX₁ and RED₂respectively, in each case with an increase in the absorbance in thevisible region of the spectrum, where the weakly coloured or colourlessform is re-formed in each case after charge equalization and, in atleast one of the resultant substances RED₁ or OX₂, the mutual conversionof oxidized and reduced form takes place through breaking or formationof a σ-bond (DE 196 05 448) or at least one of the resultant substancesRED₁ and OX₂ are linked covalently to one another via a bridge.

[0019] The cell according to the invention preferably containselectrochromic media in which

[0020] a) the reducible substance has at least one, preferably at leasttwo, chemically reversible reduction waves in the cyclic voltammogramand the oxidizable substance correspondingly has at least one,preferably at least two, chemically reversible oxidation waves, or

[0021] b) the reducible substance and the oxidizable substance arecovalently bonded to one another via a bridge B, or

[0022] c) the reducible and/or oxidizable substance selected are thosein which the reversible transition between the oxidizable form and thereducible form or vice versa is associated with the breaking orformation of a σ-bond, or

[0023] d) the reducible substance and/or the oxidizable substance aremetal salts or metal complexes of metals which exist in at least twooxidation states, or

[0024] e) the reducible and/or oxidizable substance are oligomers andpolymers which contain at least one of said redox systems, oralternatively pairs of such redox systems, as defined under a) to d), or

[0025] f) the reducible and/or oxidizable substance employed aremixtures of the substances described in a) to e), provided thesemixtures comprise at least one reducible and at least one, oxidizableredox system.

[0026] Through selection of the electrochromic compounds RED₁ and OX₂and/or mixtures thereof, any desired hues can be established. Thepreferred grey shades can be established in a known manner throughsuitable mixing of trichromatic colours (Colour Physics for Industry,Roderick McDonald, ed., Society of Dyers and Colourists, 1987 and WO98/44384).

[0027] OX₂ and RED₁ which are suitable for the purposes of the inventionare substances which, on reduction or oxidation at the cathode or anoderespectively in said solvent, give products RED₂, and OX₁ which do notundergo any secondary chemical reaction, but instead can be fullyoxidized or reduced back into OX₂ and RED₁.

[0028] Suitable reducible substances OX₂ are, for example:

[0029] in which

[0030] R² to R⁵, R⁸, R⁹, R¹⁶ to R¹⁹, independently of one another, areC₁- to C18-alkyl, C₂- to C₁₂-alkenyl, C₄- to C₇-cycloalkyl, C₇- toC₁₅-aralkyl or C₆- to C₁₀-aryl, or

[0031] R⁴; R⁵ or R⁸; R⁹ together can form a —(CH₂)₂— or —(CH₂)₃— bridge,

[0032] R⁶, R⁷ and R²² to R²⁵, independently of one another, are hydrogen, C₁- to C₄-alkyl, C₁- to C₄-alkoxy, halogen, cyano, nitro or C₁- toC₄-alkoxycarbonyl, or

[0033] R²²; R²³ and/or R²⁴; R²⁵ can form a —CH═CH—CH═CH bridge,

[0034] R¹⁰; R¹¹, R¹⁰; R¹³, R¹²; R¹³ and R¹⁴; R¹⁵, independently of oneanother, are hydrogen or in pairs are a —(CH₂)₂—, —(CH₂)₃— or —CC═Ch—bridge,

[0035] R²⁰ and R²¹, independently of one another, are O, N—CN, C(CN)₂ orN—C₆— to C₁₀-aryl,

[0036] R²⁶ and R²⁷ are hydrogen, C₁- to C₄-alkyl, C₁- to C₄-alkoxy,halogen, cyano, nitro, C₁- to C₄-alkoxycarbonyl or C₆- to C₁₀-aryl,

[0037] R⁶⁹ to R⁷⁴, R⁸⁰ and R⁸¹, independently of one another, arehydrogen or C₁- to C₆-alkyl, and

[0038] R⁶⁹ to R⁷⁴, independently of one another, are additionally aryl,or

[0039] R⁶⁹; R¹², R⁷⁰; R¹³, R⁷³; R⁸⁰ and/or R⁷⁴; R⁸¹ together form a—CH═CH—CH═CH— bridge,

[0040] E¹ and E², independently of one another, are O, S, NR¹ orC(CH₃)₂, or

[0041] E¹ and E² together form an —N—(CH₂)₂—N— bridge,

[0042] R¹ is C₁- to C₁₈-alkyl, C₂- to C₁₂-alkenyl, C₄- to C₇-cycloalkyl,C₇- to C₁₅-aralkyl or C₆- to C₁₀-aryl,

[0043] Z¹ is a direct bond, —CH═CH—, —C(CH₃)═CH—, —C(CN)═CH—, —CCl═CCl—,—C(OH)═CH—, —CCl═CH—, —C≡C—, —CH═N—N═CH—, —C(CH₃)═N—N═C(CH₃)—,—CCl═N—N═CCl— or —C₆H₄—,

[0044] Z² is —(CH₂)r or —CH₂—C₆H₄—CH₂—,

[0045] r is an integer from 1 to 10,

[0046] R⁹⁴ and R⁹⁵, independently of one another, are hydrogen or cyano,

[0047] R¹⁰¹ to R¹⁰⁵, independently of one another, are C₆- to C₁₀-arylor an optionally benzo-fused aromatic or quasi-aromatic five- orsix-membered heterocyclic ring,

[0048] R¹⁰⁷, R¹⁰⁹, R¹¹³and R¹¹⁴, independently of one another, are aradical of the formulae (CV) to (CVII)

[0049] R¹⁰⁸, R¹¹⁵ and R¹¹⁶, independently of one another, are C₆- toC₁₀-aryl or a radical of the formula (CV)

[0050] R¹¹⁰ to R¹¹², R¹¹⁷ and R¹¹⁸, independently of one another, arehydrogen, C₁- to C4-alkyl, halogen or cyano,

[0051] E¹⁰¹ and E¹⁰², independently of one another, are O, S or N—R¹¹⁹,

[0052] R¹¹⁹ and R¹²², independently of one another, are C₁- C₁₈-alkyl,C₂- to C₈-alklenyl, C₄- to C₇-cycloalkyl, C₇- to C₁₅-aralkyl or C₆- toC₁₀-aryl,

[0053] R¹⁰⁶, R¹²⁰, R¹²¹, R¹²³ and R¹²⁴, independently of one another,are hydrogen, C₁- to C₄-alkyl, C₁- to C₄-alkoxy, halogen, cyano, nitroor C₁- to C₄-alkoxycarbonyl or

[0054] R¹²⁰, R¹²¹ or R¹²³, R¹²⁴ together form a —CH═CH—CH═CH— bridge,

[0055] A¹, A² and A³, independently of one another, are O or C(CN)₂,

[0056] R⁹⁶ is hydrogen, phenyl or tert-butyl and

[0057] X⁻ is an anion which is redox-inert under the conditions.

[0058] Examples of suitable oxidizable substances RED₁ are, for example,

[0059] in which

[0060] R²⁸ to R³¹ , R³⁴, R³⁵, R³⁸, R³⁹, R⁴⁶, R⁵³ and R⁵⁴, independentlyof one another, are C₁- to C₁₈-alkyl, C₂- to C₁₂-alkenyl, C₄- toC₇-cycloalkyl, C₇- to C₁₅-aralkyl or C₆- to C₁₀-aryl,

[0061] R³², R³³, R³⁶, R³⁷, R⁴⁰, R⁴¹, R⁴² to R⁴⁵, R⁴⁷, R⁴⁸, R⁴⁹ to R⁵²,R⁵⁵ to R⁵⁸ and R⁹⁷ to R¹⁰⁰, independently of one another, are hydrogen,C₁- to C₄-alkyl, C₁- to C₄-alkoxy, halogen, cyano, nitro, C₁- toC₄-alkoxycarbonyl, C₆- to C₁₀-aryl or C₆- to C₁₀-aryloxy,

[0062] and

[0063] R⁵⁷ and R⁵⁸ are additionally an aromatic or quasi-aromatic, five-or six-membered heterocyclic ring, which is optionally benzo-fused, andR⁴⁸ is additionally NR⁷⁵R⁷⁶, or p0 R⁴⁹; R⁵⁰, R⁵¹; R⁵² and/or R⁴⁸; R⁹⁷ orR⁴⁸; R⁹⁹, R⁹⁷; R⁹⁸ or R⁹⁸; R¹⁰⁰, independently of one another, form a—(CH₂)₃—, —(CH₂)₄—, —(CH₂)₅— or —CH═CH—CH═CH— bridge,

[0064] Z³ is a direct bond, a —CH═CH— or —N═N— bridge,

[0065] ═Z⁴═ is a direct double bond, a ═CH—CH═or ═N—N═ bridge,

[0066] E³ to E⁵, E¹⁰ and E¹¹, independently of one another, are O, S,NR⁵⁹ or C(CH₃)₂, and

[0067] E⁵ is additionally C═O or SO₂,

[0068] E³ and E⁴, independently of one another, may additionally be—CH═CH—,

[0069] E⁶ to E⁹, independently of one another, are S, Se or NR⁵⁹,

[0070] R⁵⁹, R⁷⁵ and R⁷⁶, independently of one another, are C₁- toC₁₂-alkyl, C₂- to C₈-alkenyl, C₄- to C₇-cycloalkyl, C₇- to C₁₅-aralkylor C₆- to C₁₀-aryl,

[0071] and

[0072]⁷⁵ is additionally hydrogen or R⁷⁵ and R⁷⁶ in the meaning ofNR⁷⁵R⁷⁶ are, together with the N atom to which they are bonded, a five-or six-membered ring, which optionally contains further heteroatoms,

[0073] R⁶¹ to R⁶⁸, independently of one another, are hydrogen, C₁- toC₆-alkyl, C₁- to C₄-alkoxy, cyano, C₁- to C₄-alkoxycarbonyl or C₆- toC₁₀-aryl, and

[0074] R⁶¹; R⁶² and R⁶⁷; R⁶⁸, independently of one another, additionallyform a —(CH₂)₃—, —(CH₂)₄— or —CH═CH—CH═CH— bridge, or

[0075] R⁶²; R⁶³, R⁶⁴; R⁶⁵ and R⁶⁶; R⁶⁷ form an —O—CH₂CH₂—O— or—O—CH₂CH₂CH₂—O— bridge,

[0076] v is an integer between 0 and 100,

[0077] R⁸², R⁸³, R⁸⁸ and R⁸⁹, independently of one another, are C₁- toC₁₈-alkyl, C₂- to C₁₂-alkenyl, C₄- to C₇-cycloalkyl, C₇- to C₁₅-aralkylor C₆- to C₁₀-aryl,

[0078] R⁸⁴ to R⁸⁷ and R⁹⁰ to R⁹³, independently of one another, arehydrogen or C₁- to C₆-alkyl, or

[0079] R⁸⁴; R⁸⁶, R⁸⁵; R⁸⁷, R⁹⁰; R⁹² and/or R⁹¹; R⁹³ together form a—CH═CH—CH═CH— bridge.

[0080] Likewise suitable as RED₁ are anions, such as, for example, I⁻,I₃ ⁻, Br⁻ and SCN⁻.

[0081] Examples of optionally oligomeric or polymeric redox systemswhich are linked via a bridge B are those of the formula

Y—[—(—B—Z—)_(a)—(—B—Y—)_(b)—]_(c)—B—Z   (L),

[0082] in which

[0083] Y and Z, independently of one another, are a radical OX₂ or RED₁,

[0084] where

[0085] OX₂ is the radical of a reversibly electrochemically reducibleredox system, and

[0086] RED₁ is the radical of a reversibly electrochemically oxidizableredox system,

[0087] B is a bridging unit,

[0088] c is an integer from 0 to 1000, and

[0089] a and b, independently of one another, are an integer from 0 to100.

[0090] (a+b).c is preferably ≦10,000.

[0091] The term reversibly electrochemically reducible or oxidizablehere is taken to mean that the electron transfer can take place with orwithout a change in the σ-structure, entirely in the sense of theabovementioned definition of the OX₂ and RED₁ according to theinvention.

[0092] In particular, the electrochromic compounds of the formula (L)are taken to mean oligomeric compounds of the formulae

OX₂-B-RED₁   (La),

OX₂-B-RED₁-B-OX₂   (Lb),

RED₁-B-OX₂-B-RED₁   (Lc),

OX₂-(B-RED₁-B-OX₂)_(d)-B-RED₁   (Ld),

OX₂-(B-OX₂)_(e)-B-OX₂   (Le),

RED₁-(B-RED₁)_(e)-B-RED₁   (Lf)

[0093] in which

[0094] OX₂, RED₁ and B are as defined above,

[0095] d is an integer from 1 to 5, and

[0096] c is an integer from 0 to 5,

[0097] where OX₂, RED₁ and/or B, in particular if d and/or e are >1, canhave different meanings in each recurring unit.

[0098] In particular, the electrochromic compounds of the formula (L)are taken to mean polymeric compounds of the formulae

OX₂-(B-RED₁-B-OX₂)_(d)-B-RED₁   (Ld),

OX₂-(B-OX₂)_(e)-B-OX₂   (Le),

RED₁-(B-RED₁)_(e)-B-RED₁   (Lf),

[0099] in which

[0100] OX₂, RED₁ and B are as defined above,

[0101] d is an integer from 5 to 100,000, preferably from 10 to 10,000,and

[0102] e is an integer from 5 to 100,000, preferably from 10 to 10,000,

[0103] where OX₂, RED₁ and/or B, in particular if d and/or e are >1, canhave different meanings in each recurring unit.

[0104] Oligomeric or polymeric electrochromic compounds which do notconform to the formula (L) are, in particular, side-chain polymers ofthe formulae

. . . -(D)_(Γ). . . -(E-B¹-Y)_(g)- . . . -(F-B²-Z)_(h)- . . .   (CL) and

. . . -(D)_(Γ). . . -[E-(B¹-Y)_(i)-(B²-Z)_(j)]_(g)- . . . -(F-B²-Z)_(h)-. . .   (CLX),

[0105] in which

[0106] D, E and F are components of an oligomer or polymer chain, wherethe units D, E and F may be either randomly distributed or arranged inblocks,

[0107] B¹ and B² are a bridging unit,

[0108] Y and Z, independently of one another, are a radical OX₂ or RED₁,

[0109] where

[0110] OX₂ is the radical of a reversibly electrochemically reducibleredox system, and

[0111] RED₁ is the radical of a reversibly electrochemically oxidizableredox system,

[0112] f, g and h, independently of one another, are an integer from 1to 100,000, in particular from 1 to 10,000,

[0113] where

[0114] f+g+h>2,

[0115] f and h, independently of one another, may alternatively be 0,and

[0116] i and j, independently of one another, are an integer from 1 to100, in particular from 1 to 10, very particularly 1 or 2.

[0117] In particular, the oligomers or polymers of the formula (CL) aretaken to mean those of the formulae

. . . -(D)_(Γ). . . -(E-B¹-OX₂)_(g)- . . . -(F-B²-RED₁)_(h)- . . .  (CLa),

. . . -(D)_(Γ). . . -(E-B¹-OX₂)_(g)-   (CLb),

. . . -(D)_(Γ). . . -(F-B²-RED₁)_(h)- . . .   (CLc),

. . . -(D)_(Γ). . . -[E-B¹-OX₂-B²-RED₁]_(g)- . . .   (CLXa) or

. . . -(D)_(Γ). . . -[F-B²-RED₁-B¹-OX₂]_(h)- . . .   (CLXb)

[0118] in which

[0119] f is an integer from 0 to 10,000,

[0120] g and h, independently of one another, are an integer from 1 to10,000, preferably from 1 to 1000, particularly preferably from 1 to100, and

[0121] the other radicals are as defined above,

[0122] where OX₂ and/or RED₁, in particular if g and/or h are >1, canhave different meanings in each recurring unit.

[0123] f is preferably >10.(g+h), particularly preferably >100.(g+h).

[0124] The terms OX₂ and RED₁ in the formulae (L) and (La) to (Lf) and(CL) and (CLa) to (CLc) and (CLX) and (CLXa) to (CLXb) are taken tomean, in particular, radicals of the above-described redox systems ofthe formulae (I) to (X), (CI) to (CIV) and (XX) to (XXXIII), where thebonding to the bridging unit B, B¹ or B² takes place via one of theradicals R² to R¹⁹, R²² to R²⁷, R²⁸ to R⁵⁸, R⁶¹, R⁶², R⁶⁷, R⁶⁸, R⁸³,R⁸⁸, R¹²² or, if one of the radicals E¹ or E² is NR¹ or one of theradicals E³ to E¹¹ is NR⁵⁹ or one of the radicals E¹⁰¹ to E¹⁰² is NR¹¹⁹,via R¹, R⁵⁹ or R¹¹⁹, and said radicals then represent a direct bond, and

[0125] B, B¹ or B², independently of one another, are a bridge of theformula —(CH₂)_(n)— or —Y¹ ₅—[(CH₂)_(m)—Y²]_(o)—(CH₂)_(p)—, which may besubstituted by C₁- to C₄-alkyl, C₁- to C₄-alkoxy, halogen or phenyl,

[0126] Y¹ to Y³, independently of one another, are O, S, NR⁶⁰, COO,CONH, NHCONH, cyclopentanediyl, cyclohexanediyl, phenylene ornaphthylene,

[0127] R⁶⁰ is C₁- to C₆-alkyl, C₂- to C₆-alkenyl, C₄- to C₇-cycloalkyl,C₇- to C₁₅-aralkyl or C₆- to C₁₀-aryl,

[0128] n is an integer from 1 to 12,

[0129] m and p, independently of one another, are an integer from 0 to8,

[0130] o is an integer from 0 to 6, and

[0131] q and s, independently of one another, are 0 or 1,

[0132] where, for o>1, Y² and in may be different in each recurringunit.

[0133] OX₂ or RED₁ in said formulae (L) and (La) to (Lf) and (CL) and(CLa) to (CLc) and (CLX) and (CLXa) to (CLXb) are likewise taken to meanmetal complexes if they can be bonded to the bridging units B, B¹ or B²via a covalent bond. An example which may be mentioned is ferrocene.

[0134] OX₂ and RED₁ in the formulae (L) and (La) to (Lf) and (CL) and(CLa) to (CLc) and (CLX) and (CLXa) to (CLXb) are very particularlytaken to mean radicals of the above-described redox systems of theformulae (I), (V), (XX), (XXII), (XXIII), (XXV), (XXVI) and (XXXIII) andfor RED₁ ferrocene.

[0135] D, E and F in the formulae (CL) and (CLa) to (CLc) and (CLX) and(CLXa) to (CLXb) are taken to mean units which result in theconstruction of oligo- or polyacrylates, -methacrylates, -styrenes,-siloxanes, -carbonates, -amides, -esters, -ureas, -urethanes or-saccharides. In particular, they are taken to mean oligo- andpolyacrylates, -methacrylates and -styrenes and co-oligomers orcopolymers thereof.

[0136] D preferably conforms to the formula

—CHY¹⁰—CHY¹¹—  (CLXXI) and

[0137] E and F preferably conform, independently of one another, to theformula

—CHY¹²—CHY¹³—  (CLXXII),

[0138] in which

[0139] Y¹⁰ and Y¹², independently of one another, are hydrogen or C₁- toC₄-alkyl,

[0140] Y¹¹ is hydrogen, halogen, C₁- to C₄-alkyl, aryl or —COO—C₁- toC₈-alkyl, and

[0141] Y¹³ is a direct bond or one of the bridges of the formula —O—,—CO—O—, —CO—NH— or —C₆H₄— to B¹ or B².

[0142] Examples are according to the formula (La)

[0143] according to the formula (Lb)

[0144] according to the formula (Lc)

[0145] according to the formula (Ld)

[0146] according to the formula (Le)

[0147] according to the formula (Lf)

[0148] in which

[0149] m is an integer from 1 to 5,

[0150] u is 0 or 1, and

[0151] the other radicals are as defined above,

[0152] Examples are according to the formula (CLa)

[0153] according to the formula (CLb)

[0154] according to the formula (CLc)

[0155] according to the formula (CLXa)

[0156] Examples of metal salts or metal complexes which can be employedas OX₂ or RED₁ are Fe^(3+/2+), Ni^(3+/2+), Co^(3+/2+), Cu^(2+/+),[Fe(CN)₆]^(3−/4−), Fe₄[Fe(CN)₆]₃ ^(0/4−), [Co(CN)₆]^(3−/4−),[Fe(cyclopentadienyl)₂]^(0/+), Lu(Pc)²⁺ to ²⁻ (Pc=phthalocyanine),Fe[Fe(CN)₆]^(0/1−).

[0157] Suitable counterions for metal ions and cationic complexes areall redox-inert anions X⁻, as described in greater detail below, andsuitable counterions of the anionic complexes are all redox-inertcations M⁺, for example alkali metals or quaternized ammonium salts,such as Na⁺, K⁺, N(CH₃)₄ ⁺, N(C₄H₉)₄ ⁺, C₆H₅CH₂N(CH₃)₃ ⁺ and others.

[0158] Preference is likewise given to an electrochromic filter whichcomprises mixtures of the electrochromic substances mentioned above ingeneral terms and as preferred. Examples of such mixtures are(I)+(CI)+(XXVI), (I)+(IV)+(XXII), (La)+(I)+(XXVI), (La)+(CI),(LX)+(LXI), (LXV)+(XXVI), (CLII)+(XXVI), but this should not be taken tomean an expression of any restriction.

[0159] The mixing ratios are variable within broad limits. They allowoptimization of a desired hue, in particular a grey shade, and/oroptimization of the desired dynamics of the device.

[0160] In the abovementioned substituent meanings, alkyl radicals,including derivatives, for example alkoxy or aralkyl radicals, arepreferably those having 1 to 12 carbon atoms, in particular having 1 to8 carbon atoms, unless stated otherwise. They can be straight-chain orbranched and can optionally contain further substituents, such as C₁- toC₄-alkoxy, fluorine, chlorine, hydroxyl, cyano, C₁- to C₄-alkoxycarbonylor COOH.

[0161] The term cycloalkyl radicals is preferably taken to mean thosehaving 3 to 7 carbon atoms, in particular having 5 or 6 carbon atoms.

[0162] Alkenyl radicals are preferably those having 2 to 8 carbon atoms,in particular 2 to 4 carbon atoms.

[0163] Aryl radicals, including those in aralkyl radicals, are phenyl ornaphthyl radicals, in particular phenyl radicals. They can besubstituted by 1 to 3 of the following radicals: C₁- to C₆-alkyl, C₁- toC₆-alkoxy, fluorine, chlorine, bromine, cyano, hydroxyl, C₁- toC₆-alkoxycarbonyl or nitro. Two adjacent radicals may also form a ring.

[0164] The term optionally benzo-fused aromatic or quasi-aromatic five-or six-membered heterocyclic rings is taken to mean, in particular,imidazole, benzimidazole, oxazole, benzoxazole, thiazole, benzothiazole,indole, pyrazole, triazole, thiophene, isothiazole, benzisothiazole,1,3,4- or 1,2,4-thiadiazole, pyridine, quinoline, pyrimidine andpyrazine. They may be substituted by 1 to 3 of the following radicals:C₁- to C₆-alkyl, C₁- to C₆-alkoxy, fluorine, chlorine, bromine, cyano,nitro, hydroxyl, mono- or di-C₁- to C₆-alkylamino, C₁- toC₆-alkoxycarbonyl, C₁- to C₆-alkylsulphonyl, C₁- to C₆-alkanoylamino,phenyl or naphthyl. Two adjacent radicals may also form a ring.

[0165] The electrochromic substances are either known (Topics in CurrentChemistry, Vol.92, pp. 1-44, (1980), Angew. Chem. 90, 927 (1978), Adv.Mater. 3, 225, (1991), DE-A-3 917 323, J. Am. Chem. Soc.- 117, 8528(1995), J. C. S. Perkin II 1990, 1777, DE-A-4 435 211, EP-A-476 456,EP-A-476 457, DE-A-4 007 058, J. Org. Chem. 57, 1849 (1992) and J. Am.Chem. Soc. 99, 6120, 6122 (1977) or can be prepared analogously. Thecompounds of the formula (L) are likewise known (WO 97/30134) or can besynthesized from building blocks which are known per se, for example inaccordance with the following scheme:

[0166] The compounds of the formula (CL) and (CLX) can be prepared bypolymerization from building blocks which are known per se, for examplethe following:

[0167] The polymerization is preferably carried out in a solvent, forexample dimethylformamide, with addition of a free-radical initiator,for example azobisisobutyronitrile, at from room temperature to theboiling point of the medium, preferably at 40-80° C.

[0168] Synthetically required ions, such as bromide, are subsequentlyreplaced by redox-inert ions.

[0169] Particular preference is given to the electrochromic compounds ofthe formulae (I), (II), (III), (IV), (V), (XX), (XXII), (XXIII), (XXVI),(XXVII) and ferrocene, and the bridged compounds of the formula (L) orside-chain polymers of the formula (CL) or (CLX) containing at least oneof these formulae as OX₂ or RED₁.

[0170] In this selection and likewise in the particular and exceptionalselections listed below of electrochromic compounds, it must always beensured that the electrochromic medium contains at least one OX₂ and atleast one RED₁. If, for example, OX₂=formula (I), the electrochromicmedium must also contain an RED₁, preferably from the selection of thepreferred RED₁ of the formulae (XX), (XXII), (XXIII), (XXVI) and(XXVII), but also from the above selection, listed in general terms, ofthe RED₁ of the formulae (XX) to (XXXIII) and the abovementioned metalsalts, complexes or anions X⁻ which are suitable as RED₁. This alsoapplies analogously to the preferred and particularly preferred RED₁.

[0171] Very particular preference is given to the electrochromiccompounds of the formulae (I), (II), (IV), (V), (XXII) (XXIII), (XXVI)and (XXVII)

[0172] in which

[0173] R², R³, R⁸ and R⁹, independently of one another, are methyl,ethyl, propyl, butyl, pentyl, hexyl, heptyl, benzyl, phenethyl,phenylpropyl, phenyl, 2-methylphenyl or 2,6-dimethylphenyl, or

[0174] R⁸ and R⁹ together form a —(CH₂)₂— or —(CH₂)₃— bridge,

[0175] R¹⁰ to R¹⁵ are hydrogen,

[0176] R⁶⁹ to R⁷³, R⁸⁰ and R⁸¹, independently of one another, arehydrogen or methyl, or

[0177] R¹²; R⁶⁹, R¹³; R⁷⁰, R⁷³; R⁸⁰ and/or R⁷⁴; R⁸¹ form a —CH═CH—CH═CH—bridge,

[0178] Z¹ is a direct bond or —CH═CH—,

[0179] Z² is —(CH₂)_(r)—,

[0180] r is an integer from 2 to 6,

[0181] X⁻ is an anion which is redox-inert under the conditions,

[0182] R³⁴, R³⁵, R³⁸ and R³⁹, independently of one another, are methyl,ethyl, propyl, butyl, benzyl, phenethyl, phenylpropyl or phenyl,

[0183] R³⁶ and R³⁷ are hydrogen,

[0184] Z³ is a direct bond or a —CH═CH— bridge,

[0185] Z⁴ is a direct double bond,

[0186] R⁴⁰ and R⁴¹ are identical and are hydrogen or methyl,

[0187] E³ and E⁴ are identical and are S, N—R⁵⁹ or C(CH₃)₂,

[0188] E⁵ is NR⁵⁹

[0189] E⁶ to E⁹ are identical and are S,

[0190] R⁴⁷, R⁴⁸, R⁹⁷ and R⁹⁸, independently of one another, arehydrogen, methyl, methoxy, cyano, phenyl or phenoxy,

[0191] R⁴⁹ to R⁵², independently of one another, are hydrogen, methyl,cyano or methoxycarbonyl, or

[0192] R⁴⁹; R⁵⁰ and/or R⁵¹; R⁵² form a —(CH₂)₃— or —CH═CH—CH═CH— bridge,

[0193] R⁴⁶ and R⁵⁹, independently of one another, are methyl, ethyl,propyl, butyl or phenyl, and

[0194] R⁹⁹ and R¹⁰⁰ are hydrogen,

[0195] and the bridged compounds of the formula (L), in particular ofthe formula (La), which contain at least one of these formulae as OX₂ orRED₁, where

[0196] B is —(CH₂)_(n)— and

[0197] n is an integer from 3 to 6,

[0198] and the side-chain polymers of the formula (CL) and (CLX), inparticular of the formula (CLXa), which contain at least one of theseformulae as OX₂ or RED₁,

[0199] where

[0200] D is the formula (CLXXI),

[0201] E and F are the formula (CLXXII),

[0202] Y¹⁰ and Y¹², independently of one another, are hydrogen ormethyl,

[0203] Y¹¹ is —COOCH₃ or —COOCH₂CH₂OCH₂CH₃,

[0204] Y¹³ is a bridge of the formulae —CO—O— or —C₆H₄— or B¹ or B²,

[0205] B¹ and B², independently of one another, are a bridge of theformulae —(CH₂)_(n)—, and

[0206] n is an integer from 1 to 6.

[0207] Very outstandingly suitable for the purposes of the invention arethe electrochromic compounds of the formulae (I) and (II)

[0208] in which

[0209] R² and R³ are identical and are methyl, ethyl, butyl, heptyl orphenylpropyl,

[0210] R¹² to R¹⁵ and R⁶⁹ to R⁷² are hydrogen,

[0211] Z¹ is a direct bond,

[0212] Z² is —(CH₂)₃— or —(CH₂)₄—, and

[0213] X⁻ is a redox-inert anion or I⁶³¹ .

[0214] Very outstandingly suitable for the purposes of the invention arethe electrochromic compounds of the formula (XXVI)

[0215] in which

[0216] E⁵ is NR⁵⁹,

[0217] R⁴⁶ and R⁵⁹, independently of one another, are methyl, ethyl,propyl, butyl, phenylpropyl or phenyl,

[0218] R⁴⁷, R⁴⁸, R⁹⁷ and R⁹⁸, independently of one another, arehydrogen, phenyl or phenoxy, and

[0219] R⁹⁹ and R¹⁰⁰ are hydrogen.

[0220] Likewise very outstandingly suitable for the purposes of theinvention are the electrochromic compounds of the formula (La)

[0221] in which

[0222] OX₂ is a radical of the formula (I),

[0223] RED₁ is a radical of the formula (XXVI), and

[0224] B is —(CH₂)_(n)—,

[0225] where

[0226] n is an integer from 3 to 6,

[0227] R² and R⁴⁶ are a direct bond to B,

[0228] R³, R¹² to R¹⁵, R⁶⁹ to R⁷², Z¹ and X⁻ have the outstandingmeaning given above,

[0229] R⁴⁷, R⁴⁸, R⁹⁷ to R¹⁰⁰ are hydrogen or a maximum of 2 of theradicals R⁴⁷, R⁴⁸, R⁹⁷ and R⁹⁸ are phenoxy,

[0230] E⁵ is NR⁵⁹, and

[0231] R⁵⁹ is methyl, ethyl, butyl, heptyl, phenylpropyl or phenyl.

[0232] Likewise very outstandingly suitable for the purposes of theinvention are the electrochromic compounds of the formula (CLXa)

[0233] in which

[0234] OX₂ is a radical of the formula (I),

[0235] RED₁ is a radical of the formula (XXVI),

[0236] D is the formula (CLXXI),

[0237] E is the formula (CLXXII),

[0238] Y¹⁰ and Y¹², independently of one another, are hydrogen ormethyl,

[0239] Y¹¹ is —COOCH₂CH₂OCH₂CH₃,

[0240] Y¹³ is a bridge of the formulae —CO—O— or —C₆H₄— to B¹ or B²,

[0241] B¹ and B², independently of one another, are a bridge of theformulae —(CH₂)_(n)—,

[0242] where

[0243] n is an integer from 1 to 6,

[0244] R² is a direct bond to B¹,

[0245] R³ and R⁴⁶ are a direct bond to B²,

[0246] R¹² to R¹⁵, R⁶⁹ to R⁷², Z¹ and X⁻ have the outstanding meaninggiven above,

[0247] R⁴⁷, R⁴⁸, R⁹⁷ to R¹⁰⁰ are hydrogen, or a maximum of 2 of theradicals R⁴⁷, R⁴⁸, R⁹⁷ and R⁹⁸ are phenoxy,

[0248] E⁵ is NR⁵⁹ and

[0249] R⁵⁹ is methyl, ethyl, butyl, heptyl, phenylpropyl or phenyl.

[0250] The electrochromic filter according to the invention preferablycomprises, in its electrochromic medium, at least one solvent in whichthe electrochromic substances, optionally a conductive salt andoptionally further additives are dissolved. The solvent may also havebeen thickened to give a gel, for example by means of polyelectrolytes,porous solids or nanoparticles having a large active surface area.

[0251] If use is made of polymeric electrochromic compounds, inparticular of the formulae (L) to (Ld) to (Lf) and (CL) and (CLa) to(CLc) and (CLX) and (CLXa) to (CLXb), the solvent can be omitted. It isalso possible for such polymers to be mixed, for example formula (LXV)and (LXVII). Further OX₂ or RED₁ are optionally dissolved in thepolymer, for example formula (XXVI) in polymer of the formula (LXV).

[0252] Suitable solvents are all solvents which are redox-inert underthe selected voltages and which are not able to eliminate anyelectrophiles or nucleophiles or themselves react as sufficiently strongelectrophiles or nucleophiles and so could react with the colouredfree-radical ions. Examples are propylene carbonate, γ-butyrolactone,acetonitrile, propionitrile, benzonitrile, glutaronitrile,methylglutaronitrile, 3,3′-oxydipropionitrile, hydroxypropionitrile,dimethylformamide, N-methylpyrrolidone, sulpholane, 3-methylsulpholaneor mixtures thereof. Preference is given to propylene carbonate,benzonitrile and mixtures with one another or with glutaronitrile or3-methylsulpholane. Particular preference is given to propylenecarbonate. Particular preference is likewise given to benzonitrile.

[0253] The electrochromic solution may contain at least one inertconductive salt. In particular if at least one of the substances of theredox pair RED₁/OX₂ is of an ionic nature, addition of a conductive saltis unnecessary.

[0254] Suitable inert conductive salts are lithium, sodium andtetraalkylammonium salts, in particular the latter. The alkyl groups mayhave between 1 and 18 carbon atoms, and be identical or different.Preference is given to tetrabutylammonium. The anions to these salts,but also the anions X⁻ in the formulae (I) to (VI), (CI), (CII) and (CV)to (CVII) and in the metal salts are all redox-inert, colourless anions.

[0255] Examples are tetrafluoroborate, tetraphenylborate,cyanotriphenylborate, tetramethoxyborate, tetrapropoxyborate,tetraphenoxyborate, perchlorate, chloride, nitrate, sulphate, phosphate,methanesulphonate, ethanesulphonate, tetradecanesulphonate,pentadecanesulphonate, trifluoromethanesulphonate,perfluorobutanesulphonate, perfluorooctanesulphonate, benzenesulphonate,chlorobenzenesulphonate, toluenesulphonate, butylbenzenesulphonate,tert-butylbenzenesulphonate, dodecylbenzenesulphonate,trifluoromethylbenzenesulphonate, hexafluorophosphate,hexafluoroarsenate, hexafluorosilicate, 7,8- or7,9-dicarbanidoundecaborate(-1) or (-2), which are optionallysubstituted on the B and/or C atoms by one or two methyl, ethyl, butylor phenyl groups, dodecahydrodicarbadodecaborate(-2) orB-methyl-C-phenyl-dodecahydro-dicarbadodecaborate(-1).

[0256] Likewise suitable, including as anions X⁻ in the formulae (I) to(VI), (CI), (CII) and (CV) to (CVII) and in the metal salts, are theabovementioned anions, which can also take on the role of an RED₁, forexample I⁻ and I₃ ⁻.

[0257] The EC contrast plate according to the invention is operatedusing a direct current which is constants pulsed or varying inamplitude, for example varying sinusoidally. The voltage depends on thedesired colour depth, but in particular on the reduction and oxidationpotentials of the OX₂ and RED₁ used. Such potentials are given, forexample, in (S. Hünig, H. Berneth, Topics in Current Chemistry, Volume92, pp. 1-44, 1980) or (K. Deuchert, S. Hünig, Angew. Chem. 90, 927,1978) or the literature cited therein. The difference of theirpotentials is a guide value for the requisite voltage, but theelectrochromic device can also be operated at lower or higher voltage.In many cases, for example when use is made of OX₂=formula (I) or (V)and RED₁=formula (XX), (XXII), (XXVI) or (XXVII) or they are linked viaa bridge of the formula (L), in particular formula (La) to (Lf), thispotential difference necessary for operation is ≦1 V.

[0258] If the voltage is switched off, the electrochromic deviceaccording to the invention returns to its original state. This erasurecan be considerably accelerated if the contacted segments or plates areshort-circuited. Repeated reversal of the voltage, if necessary alsowith simultaneous reduction in the voltage, also allows the display tobe erased very rapidly.

[0259] By variation of the layer thickness of the electrochromic device,the viscosity of the electrochromic solution and/or the diffusion ordriftability of the electrochromic substances, the switch-on andswitch-off times of the display device can be modified within broadlimits. For example, thin layers exhibit shorter switching times thanthick ones. It is therefore possible to construct rapidly and slowlyswitchable devices and thus to provide optimum matching to theparticular applications.

[0260] In the case of slow devices, the coloration in the switched-onstate can be maintained using a power-saving or refresh mode. After thecoloration has been built up, for example by means of a direct voltageof sufficient magnitude which is constant or varying with high frequencyor pulsed, the system is switched to pulsed or varying direct voltage oflow frequency, where, during the phases in which the voltage is zero,the contacting of the conductive coating of the plates or films is notshort-circuited. This low frequency can be, for example, in the regionof 1 Hz or lower, where the duration of the switch-on and switch-offphases need not be of equal length, but instead, for example, theswitch-off phases may be significantly longer. Since the colour depthonly decreases slowly during the current pauses in thenon-short-circuited state, relatively short current pulses aresufficient to compensate for these losses again in the subsequentrefresh phase. This gives a flicker-free image with virtually constantcolour depth, but whose maintenance requires only a fraction of thecurrent which would arise in the case of permanent current flow.

[0261] The EC contrast plate can be coupled with any desired displaydevices which emit light. This applies to plasma displays,liquid-crystal displays, electroluminescent displays, vacuum fluorescentdisplays, light-emitting diodes and other types of display. It can alsobe used to attentuate the light from light sources, such as, forexample, automobile headlamps, brake lights, rear lights or ceilinglamps.

[0262] The invention furthermore relates to an EC contrast plate havingan integrated touch screen. The EC contrast plate is either constructedas a discrete unit in front of the display screen or the outer surfaceof the screen is used at least partly as substrate. The base area of theEC contrast plate is larger than the area of the screen. The part of theEC contrast plate that projects beyond the screen area serves as touchscreen and contains firstly one or more touch sensors and secondly anEC-based display unit. The sheet of the EC contrast plate facing thescreen or connected to the screen is referred to below as the carrierplate, and the other as the outer plate. A radiation source is arrangedat at least one of the faces of the transparent outer plate of the ECcontrast plate; its light enters the outer plate and illuminates it. Atleast one photodetector is mounted at the carrier plate; some or all ofthe outer-plate area lies within its photosensitive solid-angle regionso long as it projects beyond the base area of the screen.

[0263] The light propagates from the radiation source over theirradiated face of the outer plate by total reflection at the interfacesof the outer plate. When the outer-plate surface is touched with afinger, contact areas are formed between the plate and the uppermostskin layer, which comprises predominantly phosphorus lipids. The lipidlayer has a refractive index in the range from 1.5 to 1.6. This value isin the region of the refractive index of a transparent plate or evenabove it, and consequently the majority of the light totally reflectedwithout touching is no longer totally reflected at the touched point ofthe plate surface, but penetrates into the skin and is highly scatteredin it. A pale area forms in the contact zone and is detected by thephotodetector at the opposite carrier plate of the display device. Theextent and brightness of this area varies as a function of the touchpressure. Evaluation electronics of suitable design allow thesensitivity of the touch sensor to be adjusted to a desired level.

[0264] The display part of the touch screen in the part of the ECcontrast plate projecting beyond the screen can be designed as areflective display without its own light source. In this case, thecarrier plate, if it projects beyond the base area of the screen,preferably has a coating on its inside which predominantly reflects thevisible light, while being predominantly transparent to light emitted bythe radiation source at the outer plate. Alternatively, the reflectivecoating can contain a transparent area for the light of the radiationsource illuminating the outer plate, preferably in the centre of thephotosensitive solid-angle region of the photodetector. At least one ofthe electroconductive coatings is structured in the region of the partprojecting beyond the screen area, enabling information to be displayed,whilst transmission of the EC contrast plate can be varied in thisregion independently of the part of the EC contrast plate lying in frontof the screen area.

[0265] The display part of the touch screen can also be designed as atransmissive display having an additional light source forback-illumination of the part of the EC contrast plate projecting beyondthe screen area.

[0266] The outer plate preferably has a thickness of at least 0.05 mm,particularly preferably at least 0.5 mm. It can consist of any materialof low light attenuation in the spectral region of the radiation source.When assessing the light attenuation, the length which corresponds tothe greatest dimension of the plate must be considered. Preference isgiven to a material in which the light from the radiation source isattenuated by not more than 50% at a point of the outer plate withmaximum separation from the source. Preferred materials are silicateglasses, quartz glasses or transparent polymers, such as polycarbonates,polymethacrylates or polyesters.

[0267] In order to ensure good total reflection of the incident light inthe outer plate, the outer plate is preferably made of a material havinga particularly high refractive index, preferably glass having arefractive index of greater than 1.5, particularly preferably greaterthan 1.6.

[0268] Suitable radiation sources for illuminating the outer plate are,for example, tungsten lamps, light-emitting semiconductor diodes orsemiconductor laser diodes. The region of spectral sensitivity of thephotodetector must cover the emission spectrum of the radiation source.The maximum sensitivity of the photodetector and the maximum in theemission spectrum of the radiation source preferably coincide. Preferredphotodetectors are semiconductor photodetectors. Particular preferenceis given to silicon photodiodes, silicon phototransistors and silicon orsilicon/metal oxide charge-coupled devices.

[0269] In order to eliminate the influence of ambient light on the touchsensor and to avoid adversely affecting the colour setting of the ECcontrast plate, the outer plate is preferably illuminated using aradiation source whose emission spectrum is outside the visiblespectrum, for example in the infrared spectral region at a wavelengthgreater than 680 nm, preferably greater than 780 nm and particularlypreferably greater than 850 nm. The radiation source preferably emits ina spectral region in which the absorption of the display device is lowand does not change greatly even when the displayed information isswitched over.

[0270] Each photodetector is preferably followed by a unit forprocessing, the electrical signal.

[0271] An additional measure for avoiding errors caused, for example, byambient light is the use of the lock-in method (P. Cielo, OpticalTechniques for Industrial Inspection, Academic Press San Diego 1988, p.128-130). The radiation output of the radiation source is changedperiodically with time at a frequency f_(Q). Of the electrical signalsfrom the photodetector, only that part of the signal which likewisechanges periodically with time and at approximately the same frequencyas the radiation output of the radiation source is passed on in asubsequent electronic unit. The choice of the width of the acceptedfrequency band Δf_(p) of the signal from the photodetector about thefrequency f_(Q) enables the separation of desired signals andinterfering signals to be optimized. Preference is given to a relativewidth of the accepted frequency band Δf_(p)/f_(Q) of less than 0.1;particular preference is given to a relative width Δf_(p)/f_(Q) of lessthan 0.01.

[0272] The solid-angle range in which the radiation source emits shouldpreferably be matched to the illuminated face of the plate in order toachieve the fullest possible introduction of the light from theradiation source into the plate.

[0273] In order to obtain particularly good reflections of the incidentlight at the faces of the plate, one or more of the faces may be coatedwith an optically reflective material. The face illuminated by theradiation source is excepted from the coating. Due to the reflectivecoating of the faces, the incident light is reflected particularlyfrequently within the plate, i.e. it is utilized efficiently, and theplate is illuminated more uniformly. Preferred coatings are opticallyreflective metals and metal alloys, such as gold, silver, copper,nickel, tin or aluminium. Preferred coating methods are physical vacuumdeposition methods, such as vapour deposition, sputtering, ChemicalVapor Deposition (CVD) (David A. Glocker, Ismat Shah (Ed.) Handbook ofThin Film Process Technologie, Institute of Physics Publishing, Bristoland Philadelphia 1995). It is also possible to adhesively bond oncommercially available metal-coated films.

[0274] The outer plate, if it projects beyond the screen, may be dividedinto a plurality of touch fields. Touch fields are areas of the displaydevice to which is unambiguously assigned a photodetector in whosephotosensitive solid-angle region only this certain area of the displaydevice lies. When different touch fields are touched, differentphotodetectors record the scattered light generated by the touch. Thesignals from the individual photodetectors allow reconstruction of whichtouch fields were touched. The separation between two adjacent touchfields should not be smaller than the typical diameter of a humanfingertip of about 1 cm in order to avoid incorrect messages. The touchfields can be marked on the plate in a manner evident to the toucher orshown by the display.

[0275] The touch sensor can also be switched off completely or in atime-limited manner. This is advantageous in order to avoid incorrectfunctioning of the touch sensor in the case of touches which do notserve the intended purpose of switching, such as, for example, duringcleaning. Switching-off can be effected by, given a certain timesequence of touches of the sensor, the associated electrical signalsfrom the photodetector(s) initiating switching off in the downstreamunit for processing the electronic signals. Switching off can mean thatno further signals are being processed. Switching off can be timelimited or can be reversed by a further defined signal sequence.

[0276] For example, in an embodiment of the claimed device whichcomprises only one touch field, the particular time sequence of the onesignal can consist in the touch field being touched precisely threetimes in succession within a certain time, for example 5 seconds. In anembodiment of the claimed device which comprises at least two touchfields, the particular time sequence of signals can consist, forexample, in two certain touch fields being touched precisely twice insuccession simultaneously and within a certain time, for example 5seconds. This signal sequence is then further processed by thedownstream electronic signal processing device so that, for example for1 minute, no signal corresponding to touching of a touch field is passedon.

[0277] The EC contrast plate according to the invention is easy tomanufacture since the filling of the EC cell with the EC medium is easyto carry out and is much less complex than, for example, a sputteringprocess. The contrast plate has excellent light stability and allows alarge number of switching cycles.

[0278] The EC contrast plate with integrated touch screen has theadvantage of forming a single front sheet without gaps and joints. Thisis easy to clean and offers a robust surface for use in areas which havea high degree of soiling or aggressive environmental conditions or inwhich high hygiene requirements are made (foods industry).

FIGURES AND EXAMPLES

[0279] FIG. 1A shows a section through a CRT tube having an EC contrastplate which is connected to to the screen.

[0280] FIG. 1B shows a detail with layer sequence on the screen.

[0281] FIG. 2A shows a section through a CRT tube with EC contrast plateas a discrete unit in front of the screen.

[0282] FIG. 2B shows a detail with layer sequence in front of thescreen.

[0283] FIG. 3A shows a plan view of an EC contrast plate with integratedtouch screen.

[0284] FIG. 3B shows a side view of an EC contrast plate with integratedtouch screen.

[0285] FIG. 1A shows a section through a CRT tube 1. The tube has aglass envelope 2 which encloses the screen 3. The electron gun 4generates the electrons, which are focused and hit the phosphor-coatedinner surface 5 of the screen 3. An electrochromic contrast plate 6 ismounted on the outer surface of the screen.

[0286] FIG. 1B shows a detail of the screen from FIG. 1A. The phosphorlayer 5 consists of a regular pattern of phosphor spots with threedifferent colours 5R, 5G, 5B in the normal case for red, green and blue.An electrochromic contrast plate 6 is mounted on the outside of thescreen 3. The contrast plate is connected to the screen 3 through acommon sheet. The screen 3 has a transparent, electroconductive coating7. The second electrode is formed by the second transparent,electroconductive coating 8, which is located on the transparent sheet9. The electrochromic medium 10 is located between the two electrodes.The electrochromic medium 10 alters its transmission properties when anelectric voltage is applied between the two electrodes 7 and 8.

[0287] In FIG. 2A, the electrochromic device 26 is positioned in frontof the screen 3 with the interspace 21.

[0288] FIG. 2B shows a detail of the screen from FIG. 2A. Theelectrochromic contrast plate 26 consists of the transparent sheets 23and 29 with the transparent, electroconductive electrodes 27 and 28, andthe electrochromic medium 20. The space 21 between the screen 3 and theelectrochromic contrast plate 26 may be filled with a medium whichmatches the refractive index and thus reduces possible reflections.

[0289] FIGS. 3A and 3B show plan and side views respectively of an ECcontrast plate 36 with integrated touch screen. The EC contrast plate isdivided into an area having a contrast function 310 and an area with afunction as touch screen 311. The EC contrast plate 36 is located infront of the screen 3 as a discrete unit. The base area of the ECcontrast plate 36 is larger than the area of the screen 3. The part ofthe EC contrast plate which projects beyond the screen area serves astouch screen 311. The EC contrast plate 36 consists of a carrier plate32 and an outer plate 31. An electroconductive, transparent coating 33a,which is divided into discrete areas 310 and 311 corresponding to thecontrast function and the function as touch screen, is located on thecarrier plate 32. The electroconductive, transparent coating 33b islocated on the outer plate 31. The carrier plate 32 and the outer plate31 are connected by a peripheral sealing ring 34 to form a cell, inwhich the electrochromic medium 35 is located. The outer plate 31 isilluminated at its face by the radiation source 313. A photodetector 37is mounted at the carrier plate 32, with amplifier 38 and output contact39.

1. Electrochromic contrast plate (6), consisting of a pair oftransparent glass or plastic sheets (5, 9), which are provided on oneside each with an electroconductive, transparent coating (7, 8), andwhich are joined together at the sides of their conductive coating via asealing ring, and in which the volume formed by the two sheets and thesealing ring is filled with an electrochromic medium (10), characterizedin that the electrochromic medium (10) is a liquid, a gel or a polymer.2. Electrochromic contrast plate according to claim 1, characterized inthat the electrochromic medium comprises at least one pair ofelectrochromic and oxidizable or reducible substances OX₂ and RED₁. 3.Electrochromic contrast plate according to claim 1 or 2, characterizedin that an electrochromic medium is used in which a) the reduciblesubstance has at least one, preferably at least two, chemicallyreversible reduction waves in the cyclic voltammogram and the oxidizablesubstance correspondingly has at least one, preferably at least two,chemically reversible oxidation waves, or b) the reducible substance andthe oxidizable substance are covalently bonded to one another via abridge B, or c) the reducible and/or oxidizable substance selected arethose in which the reversible transition between the oxidizable form andthe reducible form or vice versa is associated with the breaking orformation of a σ-bond, or d) the reducible substance and/or theoxidizable substance are metal salts or metal complexes of metals whichexist in at least two oxidation states, or e) the reducible and/oroxidizable substance are oligomers and polymers which contain at leastone of said redox systems, or alternatively pairs of such redox systems,as defined under a) to d), or f) the reducible and/or oxidizablesubstance employed are mixtures of the substances described in a) to e),provided these mixtures comprise at least one reducible and at least oneoxidizable redox system.
 4. Electrochromic contrast plate according toone of claims 1 to 3, characterized in that the electrochromic mediumcomprises electrochromic oligomers or polymers of the formulaeY—[—(—B—Z—)_(a)—(—B—Y—)_(b)—]_(c)—B—Z   (L), in which Y and Z,independently of one another, are a radical OX₂ or RED₁, where OX₂ isthe radical of a reversibly electrochemically reducible redox system,and RED₁ is the radical of a reversibly electrochemically oxidizableredox system, B is a bridging unit, c is an integer from 0 to 1000, anda and b, independently of one another, are an integer from 0 to 100, or. . . -(D)_(Γ). . . -(E-B¹Y)_(g)- . . . -(F-B²-Z)_(h)- . . .   (CL) and. . . -(D)_(Γ). . . -[E-(B¹-Y)_(i)-(B²-Z)_(j)]_(g)- . . . -(F-B²-Z)_(h)-. . .   (CLX), in which D, E and F are components of an oligomer orpolymer chain, where the units D, E and F may be either randomlydistributed or arranged in blocks, B¹ and B² are a bridging unit, Y andZ, independently of one another, are a radical OX₂ or RED₁, where OX₂ isthe radical of a reversibly electrochemically reducible redox system,and RED₁ is the radical of a reversibly electrochemically oxidizableredox system, f, g and h, independently of one another, are an integerfrom 1 to 100,000, in particular from 1 to 10,000, where f+g+h>2, f andh, independently of one another, may alternatively be 0, and i and j,independently of one another, are an integer from 1 to 100, inparticular from 1 to
 10. 5. Electrochromic contrast plate according toclaim 4, characterized in that the electrochromic medium compriseselectrochromic side-chain oligomers or polymers of the formulae...-(D)₁-...(E-B¹-OX₂)_(f)-...-(F-B²-RED₁)_(h)-... (CLa),...-(D)₁-...(E-B¹-OX₂)_(g)- (CLb), ...-(D)₁-...(F-B²-RED₁)_(h)-...(CLc), ...-(D)₁-...[E-B¹-OX₂-B²-RED₁]_(g)-... (CLXa) or...-(D)₁-...[F-B²-RED₁-B¹-OX₂]_(h)-... (CLXb)

in which f is an integer from 0 to 10,000, g and h, independently of oneanother, are an integer from 1 to 10,000, preferably from 1 to 1000,particularly preferably from 1 to 100, and the other radicals are asdefined in claim 1, where OX₂ and/or RED₁, in particular if g and/or hare >1, can have different meanings in each recurring unit. 6.Electrochromic contrast plate according to claim 4 or 5, characterizedin that the electrochromic medium comprises electrochromic side-chainoligomers or polymers in which D represents the formula —CHY¹⁰—CHY¹¹—(CLXXI) and E and F, independently of one another, represent the formula—CHY¹²—CHY¹³— (CLXXII), in which Y¹⁰ and Y¹², independently of oneanother, are hydrogen or C₁- to C₄-alkyl, Y¹¹ is hydrogen, halogen, C₁-to C₄-alkyl, aryl or —COO—C₁— to C₈-alkyl, and Y¹³ is a direct bond orone of the bridges of the formula —O—, —CO—O—, —CO—NH— or —C₆H₄— to B¹or B².
 7. Electrochromic contrast plate according to one of claims 1 to6, characterized in that, on application of a voltage to the conductivecoatings, the colour coordinates (x, y) of the electrochromic substancesin the C.I.E. triangle are between 0.3 and 0.37, preferably between 0.31and 0.35.
 8. Electrochromic contrast plate according to one of claims 1to 7, characterized in that the transmission of the electrochromic layerin the visible region varies on variation of the strength of an appliedvoltage.
 9. Electrochromic contrast plate according to one of claims 1to 8, characterized in that the minimum transmission of theelectrochromic layer is less than 25%.
 10. Electrochromic contrast plateaccording to one of claims 1 to 9, characterized in that the maximumtransmission of the electrochromic layer is greater than 70%. 11.Electrochromic contrast plate according to one of claims 1 to 10,characterized in that, on application of a voltage to the conductivecoatings, the electrochromic layer changes transmission in less than 5minutes, preferably in less than 1 minute.
 12. Device containing anelectrochromic contrast plate according to the invention according toone of claims 1 to 10 and a screen, characterized in that the contrastplate is connected to the screen via a common sheet.
 13. Electrochromiccontrast plate with integrated touch screen (36), characterized in thatan EC contrast plate according to one of claims 1 to 11 has a largerbase area than the area of the screen (3), and, at at least one of thefaces of the outer sheet (outer plate) (31) of the EC contrast plate(36), a radiation source (313) is arranged whose light enters the outerplate (31) and illuminates it, and, at the inner sheet (carrier plate)(32), in the region which projects beyond the screen area (3), aphotodetector (37) is mounted in whose photosensitive solid-angle regionpart or all of the carrier plate (32) is located, if it projects beyondthe screen area (3).
 14. Electrochromic contrast plate with integratedtouch screen according to claim 13, characterized in that theelectroconductive, transparent coating is structured by at least one ofthe sheets of the EC contrast plate.
 15. Electrochromic contrast platewith integrated touch screen according to claim 13 or 14, characterizedin that the carrier plate has a coating which predominantly reflects thevisible light, while it is predominantly transparent to the lightemitted by the radiation source.
 16. Electrochromic contrast plate withintegrated touch screen according to claim 13 or 14, characterized inthat the carrier plate has a coating which has an area which istransparent to the light from the radiation source, preferably in thecentre of the photosensitive solid-angle region of the photodetector.17. Electrochromic contrast plate with integrated touch screen accordingto one of claims 13 to 16, characterized in that the outer plate has athickness of at least 0.05 mm and preferably at least 0.5 mm. 18.Electrochromic contrast plate with integrated touch screen according toone of claims 13 to 17, characterized in that the outer plate has arefractive index of at least 1.5 and preferably at least 1.6. 19.Electrochromic contrast plate with integrated touch screen according toone of claims 13 to 18, characterized in that the radiation source hasan emission maximum at a wavelength of greater than 680 nm, preferablygreater than 780 nm and particularly preferably greater than 850 nm. 20.Electrochromic contrast plate with integrated touch screen according toone of claims 13 to 19, characterized in that at least one and a maximumof three faces of the outer plate are coated with an opticallyreflective material.
 21. Electrochromic contrast plate with integratedtouch screen according to claim 20, characterized in that the opticallyreflective material used is gold, silver, copper, nickel or aluminium,and the coatings are produced by vapour deposition, sputtering, CVD orbonding on of metal-coated films.
 22. Electrochromic contrast plate withintegrated touch screen according to one of claims 13 to 21,characterized in that a plurality of photodetectors are mounted at thepart of the carrier plate which projects beyond the screen area, acertain region of the outer plate which is unambiguously assigned to thephotodetector being located in the photosensitive solid-angle region ofeach photodetector.
 23. Electrochromic contrast plate with integratedtouch screen according to one of claims 13 to 22, characterized in thateach photodetector is followed by a unit for processing the electricalsignal.
 24. Electrochromic side-chain oligomers or polymers of theformulae ...-(D)₁-...-(E-B¹-Y)_(g)-...-(F-B²-Z)_(h)-... (CL) and...-(D)₁-...-[E-B¹-Y)_(i)-(B²-Z)_(j)]_(g)-...-(F-B²-Z)_(h)-... (CLX),...-(D)₁-...-(E-B¹-OX₂)_(g)-...-(F-B²-RED₁)_(h)-... (CLa),...-(D)₁-...-(E-B¹-OX₂)_(g)- (CLb), ...-(D)₁-...-(F-B²-RED₁)_(h)-...(CLc), ...-(D)₁-...-[E-B¹-OX₂-B²-RED₁]_(g)-... (CLXa) or...-(D)₁-...-[F-B²-RED₁-B¹-OX₂]_(h)-... (CLXb)

in which D, E and F are components of an oligomer or polymer chain,where the units D, E and F may be either randomly distributed orarranged in blocks, B¹ and B² are a bridging unit, Y and Z,independently of one another, are a radical OX₂ or RED₁, where OX₂ isthe radical of a reversibly electrochemically reducible redox system,and RED₁ is the radical of a reversibly electrochemically oxidizableredox system, f, g and h, independently of one another, are an integerfrom 1 to 100,000, in particular from 1 to 10,000, where f+g+h>2, f andh, independently of one another, may alternatively be 0, and i and j,independently of one another, are an integer from 1 to 100, inparticular from 1 to
 10. 25. Electrochromic side-chain oligomers orpolymers according to claim 24, of the formulae . . . -(D)_(Γ). . .-(E-B¹-OX₂)_(g)- . . . -(F-B²-RED₁)_(h)- . . .   (CLa), . . . -(D)_(Γ).. . -(E-B¹OX₂)_(g)-   (CLb), . . . -(D)_(Γ). . . -(F-B²-RED₁)_(h)- . . .  (CLc), . . . -(D)_(Γ). . . -[E-B¹-OX₂-B²-RED₁]_(g)- . . .   (CLXa) or. . . -(D)_(Γ). . . -[F-B²-RED₁-B¹OX₂]_(h)- . . .   CLXb) in which f isan integer from 0 to 10,000, g and h, independently of one another, arean integer from 1 to 10,000, preferably from 1 to 1000, particularlypreferably from 1 to 100, and the other radicals are as defined in claim1, where OX₂ and/or RED₁, in particular if g and/or h are >1, can havedifferent meanings in each recurring unit.
 26. Electrochromic side-chainoligomers or polymers according to claim 24 or 25, in which D representsthe formula —CHY¹⁰—CHY¹¹— (CLXXI) and E and F, independently of oneanother, represent the formula —CHY¹²—CHY¹³— (CLXXII), in which Y¹⁰ andY¹², independently of one another, are hydrogen or C₁- to C₄-alkyl, Y¹¹is hydrogen, halogen, C₁- to C₄-alkyl, aryl or —COO—C₁- to C₈-alkyl, andY¹³ is a direct bond or one of the bridges of the formula —O—, —CO—O—,—CO—NH— or —C₆H₄— to B¹ or B².